Đáp án:
B=2018 /1+2017/2+..+2/2017+1/2018B=2018/1+2017/2+..+2/2017+1/2018
→B=1+(1+2017/2)+..+(2/2017+1)+(1/2018+1)→B=1+(1+2017/2)+..+(2/2017+1)+(1/2018+1)
→B=1+2+2017/2+..+2017+2/2017+2018+1/2018→B=1+2+2017/2+..+2017+2/2017+2018+1/2018
→B=1+2019/2+..+2019/2017+2019/2018→B=1+2019/2+..+2019/2017+2019/2018
→B=2019/2+..+2019/2017+2019/2018+1→B=2019/2+..+2019/2017+2019/2018+1
→B=2019(12+..+1/2017+1/2018+1/2019)→B=2019(12+..+1/2017+1/2018+1/2019)
→B=2019A
→A/B=1/2019<1/2018
mình đã cố gắng lắm nhưng chỉ giải được 1 bài mình xin lỗi nha đừng báo vi phạm mình